Significant improvements in animal performance, efficiency and carcass and meat quality have been made over the years through the application of standard animal breeding and selection techniques. However, such classical animal breeding techniques require several years of genetic evaluation of performance records on individual animals and their relatives and are therefore very expensive. Other efforts have been made to improve productivity and quality through the application of such management practices as the use of feed additives, animal hormonal implants and chemotherapeutics. However, there is significant political and regulatory resistance to the introduction and use of such methodologies. Such methodologies are also non-inheritable and need to be applied differently in every production system.
There is a need for methods that allow relatively easy and more efficient selection and breeding of farm animals with an advantage for an inheritable traits such as circulating leptin levels, feed intake, growth rate, body weight, carcass merit and carcass composition. The economic significance of the use of genetic markers that are associated with specific economically important traits (especially traits with low heritability) in livestock through marker-assisted selection cannot therefore be over-emphasized.
The physiological regulation of intake, growth and energy partitioning in animals is under the control of multiple genes, which may be important candidates for unraveling the genetic variation in economically relevant traits (ERT) in beef production. Polymorphisms in these candidate genes that show association with specific ERT are useful quantitative trait nucleotides for marker-assisted selection.
Bovine chromosome 14 (BTA14) harbors several quantitative trait loci (QTL) that affect intramuscular fat (marbling) (see, e.g., Casas et al., J Anim Sci. 2000 March; 78(3):560-9) and subcutaneous fat depth (SFD) (see, e.g., Moore et al., J Anim Sci. 2003 August; 81(8):1919-25) in beef cattle. Recent studies have implicated the corticotrophin-releasing hormone (CRH) gene product in enabling mobilization of energy to cope with stress by stimulating hepatic gluconeogenesis, thus, influencing fat metabolism. Functional studies of the CRH gene in other species (including in mouse (see, e.g., Stenzel-Poore et al., Endocrinology. 1992 June; 130(6):3378-86) and swine (see, e.g., Seasholtz et al., J Endocrinol. 2002 October; 175(1):89-97) have suggested that CRH is highly associated with body composition (protein and lipid metabolism). The bovine CRH gene is located on BTA14 (see, e.g., Barendse et al., Mamm Genome. 1997 January; 8(1):21-8).
CRH is a growth inhibitor causing the release of glucocorticoids that in turn stimulate the production of both pro-opiomelancortin (POMC) and leptin, which are highly associated with obesity in mammals. Additionally, CRH is most known as a stress hormone. Stress stimulates hepatic gluconeogenesis that will influence fat and protein metabolism in peripheral tissue of animals. For example, a recent study on a porcine CRH gene showed that it functions as a major regulator of neuroendocrine response to stress. It mobilizes energy to cope with stress by stimulating hepatic gluconeogenesis and influencing fat metabolism. Therefore, CRH has a high impact in regulating energy homeostasis, and consequently, it affects body composition (fat deposition) and growth (see, e.g., Murani et al., Biochem Biophys Res Commun. 2006 Apr. 7; 342(2):394-405).
There is a pronounced need in the art for useful markers for intramuscular fat (marbling) (see, e.g., Casas et al., 2000, J Anim Sci. 2000 March; 78(3):560-9) and subcutaneous fat depth (SFD) (see, e.g., Moore et al., J Anim Sci. 2003 August; 81(8):1919-25) in beef cattle.
It remains advantageous to provide further SNPs that may more accurately predict the meat quality phenotype of an animal and also a business method that provides for increased production efficiencies in livestock cattle, as well as providing access to various records of the animals and allows comparisons with expected or desired goals with regard to the quality and quantity of animals produced.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.